A dental implant is a submergible structure which is inserted in the alveolar cavity of the jawbone to permit attachment of a dental prosthesis to the implant in an edentulous region. The implant requires a healing period of up to nine months to assure bone ingrowth and clinical ossiointergration at the bone implant interface. Once the healing period is over and the implant is firmly anchored to new bone, the mucosal gum tissue above the implant is penetrated for attachment of an upper post portion to which an artificial dental prosthesis is connected.
Conventional dental implants utilize a plurality of components commonly referred to as abutments which in combination with the embedded implant form the implant system. The abutments of a conventional implant system are externally and internally threaded to permit the components to be removably interconnected to one another. The proximal end of the abutments are typically shaped in the configuration of an hexagonal nut so that a wrench may be used to interconnect the abutment to the implant. The implant also contains a threaded recess to receive an abutment and has a projection at its occlusal end which is also in an hexagonal configuration. The implant may also be externally threaded to facilitate a self-tapping insertion of the implant into the cortical bone substructure.
The array of interconnecting abutments of a conventional implant system increase the installation expense of the implant and may necessitate the assistance of an outside dental laboratory to provide the component parts. More importantly, it has now been clinically established that the use of multi-threaded interconnecting abutments unavoidably leave clearance spaces or gaps at the interface between the internal and external threads of the implant and the interconnecting abutments. These gaps represent hollow crevices which allow for microbial leakage and also act as a trap for bacteria permitting microbial colonization at the juncture between the fittings. Microbial leakage can also cause inflammatory reactions in the peri-implant soft tissue. In addition, the use of many abutment components increase the procedure time and cause complications based upon the various parts needed. Furthermore there is an increased likelihood of the many parts not fitting accurately or loosening up from the occlusal forces during chewing which can result in excessive wear and breakdown.
In addition the post abutment may need to be placed at an angle with respect to the embedded implant in order to align the artificial dental prosthesis with the other teeth of the patient. To achieve this the post abutment is either bent after installation or is preangulated. Bending the post after installation is contraindicated and can cause fatigue and breakage. Although the use of a preangulated post is preferred this currently requires at least one additional screw-like member to secure the post to the implant. This complicates the design of the preangulated post since the design must account for how the screw is to be fastened through the post to the implant. Moreover if the post abutment, screw and implant are all threaded to facilitate their interconnection this will lead to the problem of microbial leakage referred to above.
The implant system of the preferred embodiment of the present invention is a two component system utilizing a narrow gauge implant which is preferably tapered and precisely contoured to press fit into the bone receptor site. A healing cap is removably inserted into a non-threaded cavity formed in the implant to form a seal within the cavity so as to permit healing of the implant without any potential for microbial leakage. Upon removal of the cap a single post abutment component is placed into the cavity for connecting the implant to a dental prosthesis. Since the implant is non-threaded the circumference of the implant may be significantly narrower in size relative to the circumference of the conventional threaded implant. In addition, the single post abutment is seated into the implant which permits it to be preangulated at an angle of from 0.degree. to 30.degree. to achieve parallelism with adjoining implant posts or other abutments without complicating its design. Once a preangulated post is selected with the desired preangulation it is fitted into the implant and then turned relative to the longitudinal axis of the implant to achieve the desired alignment. Thereafter the post is cemented in place to the implant. A plurality of horizontally spaced serrations are preferably formed around the circumference of the implant with the serrations spaced a fixed distance apart and extending over the entire vertical height of the embedded implant or a section thereof.
In another embodiment of the present invention the post abutment includes a shaft extending from the post abutment at any desired angle relative to the longitudinal axis of the implant. In this embodiment the desired angle is formed by connecting a threaded shaft into a threaded opening in the post abutment which can be done after the post abutment is seated in the implant. The threaded opening may be formed at any desired predetermined angle with the longitudinal axis of the implant thereby establishing a predetermined angle of inclination for the threaded shaft relative to the longitudinal axis of the implant.
In another two-component embodiment of the implant system of the present invention the vertical height of the implant may be shortened to a length of less than about 6 mm which facilitates insertion into a very shallow bone receptor site. In this embodiment the implant includes lateral projections extending from a position near the apical end of the implant to give the implant lateral stability. The use of a very short implant having lateral projecting arms at the occlusal end in a spider like arrangement permits the implant to avoid contact with the maxillary sinus or the mandibular nerve and may be used in the posterior portion of the mandible and maxilla in cases where minimum vertical height of bone is available. Two implants of this type having lateral projections in a spider like arrangement may also be inserted into the bone in tandem to provide additional strength and may be aligned so that the projections interdigitate. The use of two implants of this type in tandum is particularly suited for use where bone structure is minimal in the labialpalatal dimension in a posterior portion of the mandible or maxilla.
Yet another embodiment of the invention is a unitary narrow gauge implant having an integrated abutment post forming a unitary solid implant structure containing a post abutment for use in a posteria region of the mandible and/or maxilla where the jawbone is narrow. This implant is of a very narrow gauge with an extended length of over 18 mm and preferably between 18-22 mm. Two narrow gauge implants of this type may be used in tandem.
An additional embodiment of the present invention is an implant for use with a denture which permits a denture to be removably attached to either the upper or lower jawbone and to maintain the denture in a fixed position within a patients mouth.
In yet another embodiment of the present invention the distal end of the implant body is formed with a hollow interior adapted for the insertion of a bone morphogenic protein which is known to facilitate bone osseointegration. The distal end of the implant body surrounding the hollow area is defined by a plurality of projections extending lengthwise in a direction substantially parallel to the longitudinal axis of the implant permitting the distal end to be crimped so as to form an enclosure for the insertion of a bone morphogenic protein material composition.